package org.example.utils;

/**
 * @author weigang
 * @create 2022-10-31 11:17
 */

import cn.hutool.core.util.StrUtil;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletRequest;

/**
 * IP地址
 */
@Slf4j
public class IPUtils {

    private static final String UNKNOWN_STR = "unknown";

    private IPUtils() {
        throw new IllegalStateException("Utility class");
    }

    /**
     * 获取IP地址
     * <p>
     * 使用Nginx等反向代理软件， 则不能通过request.getRemoteAddr()获取IP地址
     * 如果使用了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP地址，X-Forwarded-For中第一个非unknown的有效IP字符串，则为真实IP地址
     */
    public static String getIpAddr(HttpServletRequest request) {
        try {
            String ip = request.getHeader("x-forwarded-for");
            if (StrUtil.isEmpty(ip) || UNKNOWN_STR.equalsIgnoreCase(ip)) {
                ip = request.getHeader("Proxy-Client-IP");
            }
            if (StrUtil.isEmpty(ip) || ip.length() == 0 || UNKNOWN_STR.equalsIgnoreCase(ip)) {
                ip = request.getHeader("WL-Proxy-Client-IP");
            }
            if (StrUtil.isEmpty(ip) || UNKNOWN_STR.equalsIgnoreCase(ip)) {
                ip = request.getHeader("HTTP_CLIENT_IP");
            }
            if (StrUtil.isEmpty(ip) || UNKNOWN_STR.equalsIgnoreCase(ip)) {
                ip = request.getHeader("HTTP_X_FORWARDED_FOR");
            }
            if (StrUtil.isEmpty(ip) || UNKNOWN_STR.equalsIgnoreCase(ip)) {
                ip = request.getRemoteAddr();
            }
            return ip;
        } catch (Exception e) {
            log.error("IPUtils ERROR ", e);
            return UNKNOWN_STR;
        }
    }

}